Damping device for remote control apparatus



y 3, 1947. A. P. DAVIS ET AL 2,420,523

DAMPING DEVICE FOR REMOTE CONTROL APPARATUS Filed June 10, 1938 2 Sheets-Sheet l H HIIIH' M {my}, J J8 J7 65 M J/ m ee j J5 1 60 6/ 52 5 J? 92 1 32 a J9 22 J3 Q @240 6 38 7 4 ".1/ 5 I A5) 1/4 4g;

1947- A. P. DAVIS ET AL. 2,420,523

DAMPING DEVICE FOR REMOTE CONTROL APPARATUS Filed June 10, 1958 2' Sheets-Sheet 2 8 L j c IIOIIIIIIIIHI Patented May 13, 1947 DAMPING DEVICE FOR REMOTE CONTROL APPARATUS Arthur P. Davis, New York, and George Agins, Brooklyn, N. Y., assignors to Anna Corporation; a corporation of "New York Application June 1938; Serial 'No. 212,960

2 Claims.

This invention relates to control systems of the type in which a local or remote controlled element maybe instantaneously driven at a rate of speed and through a distance or angle corresponding to the rate and extentof movement of the controlling and controlled elements causes the engagement of the operating contacts of the follow-up heads for normal operation of the pilot motor, and the direction of the pilot motor torque is determined by the direction of the relative angular deviation between the controlling and controlled elements, so that whether the controlled element lags or leads the controlling element, the pilot motor is always energized for rotation in the direction which tends to eliminate the-said deviation.

The preferred form of the damping switch operates in response to the direction of the rela tive angular motion between the controlling and controlled elements, to change the magnitude of the normal operation voltages which are applied to the pilot motor primary windings, so that the resulting change in pilot motor torque will be in the direction to bring the controlled element into positional agreement with the controlling element in avery rapid, smooth and ethcient manner.

For a more complete understanding of the invention, reference may he had to the accompanying drawings, in which:

Figure 1 is a. schematic diagram of the control system of this invention embodying. the new damping means and illustrates a polyphase alternating current service.

Figure 2 illustrates in enlarged perspective one arrangement of a damping switch constructed in accordance with this invention;

Figure 3a; is a fragmentary view of the. transformer connections in Figure 1 illustrating'the connections for normal operation ofthe system when the follow-up heads are rotating in a counterclockwise direction.

Figure 3b is afragmentary view of the changed transformer connections of Figure 3a. which re- 2. sult from the operation of the damping switch in one direction;

Figure 3c is a similar view illustrating the changedconnections of Figure 3a. which result from the operation of thedamping switch in the oppositev direction;

Figure 4a is a fragmentary view of the transformer connections of Figure 1 for normal operation of the system when the follow-up heads are rotating in a clockwise direction as viewed in Figure-1;

Figure 4b is a similar view illustrating the connections of Figure 4a which result from the operationof the damping switch in one direction;

Figure 40 illustrates the changed connections ofFig-ure la which result from the operation of the damping switch in the oppos te direction;

Figure 5 is aschematicdiagram of the control system of this invention as adapted for the use of a single phase commutator type alternating current pilot motor; and

Figure 6 is a schematic diagram of the control system of this invention as adapted for use with a direct current pilot motor.

Referring to Figure 1 of the drawings, the controlling element, located at a local or remote station, may be a handwheel It), or other controlling device, which through gearing ll, IZ-and l3, actuates the rotors of respective low and high speed self-synchronous, rotary induction transmitters 4 and I5 of conventional form. Located atthelocal or remote station of the controlled element, are respective low and high speed self synchronous rotary induction receivers l6 and I1, also of conventional form, which are electrically connected respectively to the corresponding low and. high speed transmitters I4 and to, so that the rotors of the receivers are inpositional agreement With the rotors of the correresponding transmitters at all times. The low speed or coarse control receiver I6 is equipped with a-follow-up head I8, and the high speed or finecontrol receiver I! is equipped with a followupheadlS and a novel damping switch 29.

The two follow-up heads I8 and I9 include respective gears 22 and 23, which are coaxially journaled on sleeves 24 and 25. The sleeves 24 and 25 are secured to the frames of the respective receivers it and H, and. the shaft extensions 26 and 21 of the respective receiver rotors are free to turnwithin the respective sleeves 24 and25. The contact rings 28 and, and trolley arrangements 3B and 31, are securedto and insulated from Two long contact segments 32, 34, and two short contact segments 88, 38, are mounted on insulated disc which is secured to gear 22, and two long contact segments 33, 35, and two short contact segments 31, 38 are mounted on insulated disc 83 which is secured to gear 23. In each follow-up head, the two long segments and the two short segments are respectively diametrically opposite each other, and the two short segments are positioned in the spaces between the ends of the long segments in such fashion that an insulating gap is provided between all of the adjacent segments. Contact rollers or brushes 48 and 4| are held by light spring pressure against the corresponding contact rings 28 and 29 at all times.

The single trolley ccntactor 38 of low speed head I8 is adapted to engage contact segments 32, 34, 38, 38. Similarly, the double trolley contactor 3i of high speed head I9 is adapted to engage contact segments 33, 85, SI, 33. The trolley contactors 38 and 3! are held against the contact segments by means of light spring pressure. The contact span of the high speed double trolley contactor 3! is such that when it is centrally positioned on one of the short contact segments 37 or 38, the angular distance between either trolley and the nearer adjacent long contact segment is very short. The external electrical connections to the contact segments of the follow-up heads are made by means of conventional brushes and contact rings, not shown.

A pilot motor 21 for actuating or controlling the controlled element is provided with an extended shaft '1, which for purposes of this de scription may be considered the controlled element. Shaft 5'. is provided with the gears 58 and 58, and gear 53 serves to rotate gear 22 of low speed follow-up head l8 through the gearing 80, while gear 59 serves to rotate gear 23 of high speed follow-up head [8 through gearing 8|. Pilot motor 2! is of the induction type, having a two phase primary winding and a three phase wound rotor secondary winding 82, to which a Y-grouping of resistors 91 is connected. The primary winding includes the two windings 5| and 54 which have a common connection 58 and the extremities 52 and 53.

The gear ratios between the controlling element [8 and the transmitters l4 and I5, and between the pilot motor 2! and the follow-up heads 58 and it, and the electrical connections of the system, are such that a displacement of shaft extension 21 of high speed receiver I! will displace the attached double trolley 3| from short contact segment 39 to long contact segment 33 or 35 of high speed follow-up head l8. This will energize the pilot motor 22 for the rotation of gear 23 and its attached contact segments in the same direction and through the same angle as the displacement of shaft extension 2'! of high speed receiver l7, so that the short contact segment 33 will again centrally engage the double trolley 35, which returns the system to its synchronized condition with the pilot motor rotor shaft or controlled element 5| in positional agreement with the controlling element i8.

Low speed follow-up head It operates in a similar manner to restore the system to its synchronized condition. Condensers 88 and resistor 98 are electrically connected to the contacts of the follow-up heads 18 and 19 to suppress sparking at the contacts during the operation of the system.

Power for the pilot motor 2! is supplied from the transformers 42 and 43, whose primaries are connected in T relation to each other and to a three-phase system, to provide a three-phase to two-phase transformation by means of the well known Scott connection. Thus, one voltage is supplied at the terminals 41, 49 of transformer 42, and a second voltage, displaced by 90 in phase with respect to the first is provided at the terminals 44, 46 of transformer 43. The secondary winding of transformer 42 is provided with a Voltage tap 48, and the secondary winding of transformer 43 is provided with a midtap 45 and two intermediate voltage taps 68, 68, in order that voltages of different magnitude may be obtained on each phase of the two-phase system.

The connections between the motor 2| and the two-phase voltage supply may be changed by means of the relays 55 and 55 which are provided with the armatures 66 and 61, respectively. The armature 68 of relay 55 carries two contacts 15 and 16, which, in the normal deenergized position, engage contacts 11 and 18, respectively, and which, in the energized position, engage contacts 19 and 80, respectively. Armature 81 of relay 55 carries a contact 10, which, in the normal deenergized position, engages contacts H and i2, and which, in the energized position engages contacts 13 and 14.

The relays 55 and 5B are selectively energized by a damping switch 20 consisting essentially of contact arm 62, which at one end is fastened to a disc 86 journaled to shaft extension 21 of high speed receiver I1, and at the other end carries a contact trolley 63. The contact trolley 63 is adapted to engage contact segments 84, 65 and SI which are rigidly supported on insulated disc 83 of high speed follow-up head l8, as is illustrated in detail in Fig. 2. Contact segment 64 is electrically connected to long contact segment 33, and is provided with a stop 84 to limit the movement of trolley 63. Contact segment 65 is electrically connected to long contact segment 35, and is provided with a stop 85 for trolley 63. Contact segment 8| is positioned between and in spaced relation to the contact segments 64 and 65, so as to be insulated from them. Contact arm 62 is electrically insulated from shaft eX- tension 21, and is electrically connected to the coils of respective relays 55 and 56.

Disc 86 is provided with an edge notch 81, which is adapted to receive a spring mounted roller 88, which is secured to shaft extension 21, when double trolley 3| is centrally positioned, or nearing its central position on short contact segment 39 of high speed follow-up head [8. The light spring pressure on the roller 88, whether the roller 88 is at the bottom of the notch 81 or on the periphery of the disc 88, will cause contact trolley 63 of damping switch 28, within its limits of travel between stops 84 and 85, to move exactly with shaft extension 2'! of high speed receiver 11.

Thus, when the relative movement between shaft extension 21 and disc 83 is sufiicient to cause the engagement of contact trolley 63 with one of the stops, either 84 or 85, and the relative movement persists in the same direction, the roller 88, if it is in the notch 81, will move out of the notch and on to the periphery of disc 86. If the roller 88 is on the periphery of the disc 86 when contact trolley 83 engages one of the stops, and the relative movement continues in the same direction, the roller 88 will roll on the periphery of the disc until it reaches the sloping sides of the detent 81, when the roller will tend to roll to adamant;

the bottom-of the notch: Accord-inglywhen' the controlling" element- 1's at rest With the pilot motor: 2 or controlled element 51- in positional agreement with it, the control system of this invention will be inits normaldeenergizedcondition, with double'trolley 3| of follow-up head l9 centrally positioned on short contact segment- 39, and contacttrolley 63 of damping switch 29 con-- nag-1 positioned on contact segment 8!.

It w'illbe evident that the rotor of high speed receiver l-T will at all times be free-to rotate and assumethe positioncorresponding to the position of the rotor of high" speed transmitter l5, andw'ill'not be blocked in any manner by the engagement of damping switch trolley 63 with stops;- 84 or 85.

In the-operation-of the controlsy-st'em illustrated'in Figure 1 of the drawings, and assuming that it isin its normal deenergized condition with the pilot motor shaft El or controlled element in positional agreement withthe controlling element l0, rotation of the controlling element I0 will be transmitted-through gearing I I, l2 and l3 to the rotors of the low and high speed transmitters I 4 and i5. The resultant rotation of these rotors in a corresponding direction and angle will result in an equal and substantially simultaneous movement of the rotors of respective low andhigh speed receivers I6 and IT. The double trolley-Slofhigh speed follow-up head l9 will accordingly'be displaced to engage segment 33 0i 35; depending upon the direction of rotationofthe controlling element Hi, and thereby energize primary winding of pilot motor 2|.

Assuming that the shaft extension 27 is rotating in the counter-clockwise direction as Viewed in Figure 1, normal Voltage is supplied to the motor. Thus the extremity 53 of pilot motor winding 541s connected to end tap 41 on transformer 42 through a wire I I3, and the extremity 52' of pilotmotor winding fil'is connected through a wire H4, contactroller- 45?, contact ring 28, trolle'y arrangement as, short contact segment 38, wire H5, contact roller 4!, contact ring 29, trolley arrangement 3:, long contact segment 33, a wire I20 and wire lit to end tap 44 on transformer 43; Similarly, the common point 56 of windings 54 and 5! is connected through a wire lll', armature'contact 73, contact 12, wire H8, armature contact 75 on relay 55, contact 11', to the midtap 45 on transformer 43; The common point 50 is also connected through the wire Ill, armature contact ill on relay 56, contact H, Wire H9, armature contact 15011 relay E5 and contact T8"-to the voltage tap 48 on transformer 42, so that normal voltage is impressed on both primary windings 54 and 5! of the two-phase induction motor 21, causing it to rotate in the counter clockwise direction to eliminate the deviationbetween the controlled element l9 and the controlling element 51. These connections are shown in simplified form in Figure 3a.

If, due to failure of the electric supply to the pilot motor 2| or other causes, the pilot motor 21' is-unable to follow rapid movements of the controlling element l0, and they become displaced more than a permissible amount, trolley 30 oFlowspeed follow-up head [3 will have been advancedto a point where it no longer makes contact with short segment 38 and thereby disconnects double trolley 3| of high speed follow-up head [9 from the circuit, so that the high speed follow up head 19 will'be deprived of control, and control will lie-assumed by lowspeed follow-up head-'18;

If the pilot'motordoes not accelerate rapidly enoughto follow the movement of double trolley 3|, the relative movement between shaft extension' 2 F and :disc 83=will cause trolley 63 of damping switch 20=to engage contact 64. This closes a circuit from end tap 44 on transformer 43, through wire H ii, contact s'egment'M on damping switch 20', damping switch trolley 63; wire I2l, relay 5 5', andwire I22 to intermediate tap 69 on transformer 43. A: circuit is also completed from wire lZ-I through relay 55, and wire l'23'to intermediate tap 68 on transformer 43.

The voltage between the taps 44 and 630i transformer 43 is not sufiicient to energize relay 55, so that contacts ll and 18 are still engaged'by armature contacts 15 and 'lfirespectively. The voltage between taps 44 and'89, however, is suincient to energize the relay 56 so that its armature 6'7 rises and contacts H and 12 are disengaged by armature contact 79 which then engages contacts l3 and M; This operation changes th connections between the common point 5301 primary windings 5| and 54 of induction motor 2 I, an'dthesecondary windingtaps of transformers 42 and 432 Thus, the common point Ell is now conn'ect'edthrough Wire- Ill, armature contact- 18' on relay 56, contact 13; wire 22' to tap 69 ontransio'rmer 43'.

The common point 55) is also connected through wire Ill; armature contact 15] on relay contact 74, wire l25 to tap 49 on transformer 22. These connections are shown in simplified form in Figure 379 from which it is apparent that the maximum phase-voltages are applied to the primary windings 54 and 5|;

Since the torque produced by the pilot motor 21 i'sproportional to the square of the voltage applied to'its primary windings, it will now accelerate rapidly until-the speed of gear 23 in follow-up head [9' becomes slightly higher than the speed of shaft extension 27. occurs, contact 64 will disengage trolley 63 of damping switch Zll-and central segment 8! will engage the trolley 53; so that the damping switch hl'will have returned to itsinoperative condition. Thiswilldeenergi'ze the relay 56 and thereby restore the connection of common point 5!! of the pilot motor primarywindings to tap 4t of transformer t2 and to tap 45 of transformer 43, which is the normal operating condition outlined above. The damping switch 20, therefore, provides an additional step of acceleration for the pilot motor when it lags behind the controllingelement more than apermissible amount.

If the controlling element then is brought suddenly to zero speed, the pilot motor 2|, due to inertia of its rotating parts, will drive contact 65 into engagement with trolley 63 of damping switch 25). This will complete a circuit from end tap 46 of transformer 43 through wire I26, damping switch contact 65, trolley 63, wire [2], relay 56 and wire I22 to tap 69 on transformer 43. A circuit is also closed from wire I 2| through relay 55 and a wire I23 to tap 68 on transformer 43.

The voltage between taps 46 and 69 on transformer 43 is not sufiicient to energize relay 555 so that armature contact it remains in engagement with contacts 'H and 12. The voltage across taps 46 and 68 of transformer 43, however, is suihcient to energize the relay 55; so that its armature 66 disengages armature contacts 15 and 16 from contacts 11 and 18, respectively, and engages contacts and 18' with 79 and 80, respectively.

With this settingof-the relays 55 and 56, the" When this common point 55 of the windings and 54 is again changed to a different voltage value. Thus, the common point is connected through wire ll, armature contact 10 on relay 56, contact 12, wire H5, armature contact on relay 55, contact i9 and wire |23 to tap 68 on transformer The common point 50 is also connected through wire Ill, armature contact 10 on relay 58, contact 1|, wire H9, armature contact 16 on relay 55, contact 85 and wire |24 to tap 49 on transformer 42, The resulting connections are illustrated in the simplified diagram of Figure 3c and this arrangement will reduce the voltage which is applied to the primary winding 5| of the pilot motor 2|.

Inasmuch as the torque of the pilot motor is determined by the smaller of the two voltages which are applied to the pilot motor 2| primary windings, the torque will thereby be reduced from its normal operating value and the pilot motor 2! therefore will decelerate. The pilot motor will then drive long contact segment 33 out of engagement with double contact trolley 3| of follow-up head l9 and, when short contact segment 39 is centrally positioned under double trolley 3 I, the contact trolley 53 of damping switch will have returned to its inoperative position on central segment 8|, so that the control system will be in its normal deenergized condition with the pilot motor 2| and controlled element 51 at rest in positional agreement with the controlling element Illv If, however, due to the inertia of the rotating parts, the pilot motor has not decelerated to zero speed when short contact segment 39 is centrally positioned under double trolley 3|, the pilot motor primary winding 5| will be disconnected from transformer 43 and then the damping switch contact segment 65 will engage the trolley 63 so that the relay 55 will operate. The resulting connections are as illustrated in the simplified diagram of Figure 30, but with the connection to tap 44 of transformer 43 broken.

Upon continued rotation of the pilot motor 2|, long contact segment will engage double trolley 3| of follow-up head l9, thus closing a circuit from tap 45 of transformer 43 through a wire l25, long contact segment 35, double trolley 3|, contact ring 29, contact roller 4|, wire ||5, short contact segment 38, single trolley 30, contact ring contact roller 4!! and a wire M4 to extremity 52 of winding 5|. The phase of the voltage now applied to pilot motor primary winding 5| will be reversed, and the voltage increased, and greater than normal operating torque will be produced in the opposite direction by the pilot motor 2| to decelerate it quickly to zero speed and then accelerate it in the opposite direction. The resulting connections are shown in the simplified diagram of Figure 4c.

Upon the resulting reversal in the direction of rotation of the pilot motor 2|, contact will disengage trolley 53 of damping switch 25, and central segment 8| will momentarily engage the trolley 53, thereby deenergizing relay 55 so that the movable contacts of the relay will return to their inoperative positions, which reduces the voltages applied to the pilot motor primary windings to their normal operating values for normal operating torque, and these resulting connections are illustrated in the simplified diagram of Figure do.

After the momentary engagement of central segment 8| with trolley 63, the damping switch contact 54 will then engage the trolley 63, so

that relay 55 will be energized. Relay 55 will then transfer the connections between common point 50 of the pilot motor primary windings and the transformers, i. e., from tap 45 to tap 69 of transformer 43, and from tap 48 to tap 49 of transformer 42 as described above. With the resulting connections, which are illustrated in the simplified diagram of Figure 4b, a reduced voltage will be applied to winding 5| of the pilot motor, and the resulting reduced torque produced in the pilot motor will cause it to drive gear 23 smoothly into synchronism with shaft extension 21 of high speed receiver ll.

When synchronism is obtained, double trolley 3| will be centrally positioned on short contact segment 39 follow-up head l9, and roller 88 will be at the bottom of notch 81 in disc 88, so that the operating contacts of damping switch 20 will be disengaged, and trolley 63 will be in its inoperative position on central segment 8|. The pilot motor 2|, therefore, will be in its inoperative condition and at standstill, and the pilot motor rotor shaft or controlled element 51 will be in positional agreement with the controlling element Hi.

In the arrangement of Figure 5 wherein the control system of this invention is shown adapted for use with a single phase, commutator type alternating current pilot motor 53, the pilot motor armature 94 is electrically connected to the single phase supply, and the field winding 95 is energized by the secondary winding of supply transformer 93. Follow-up heads l8 and l9 control the selection of either end tap 99 or Hi0 of transformer 93 secondar winding, and damping switch 20 changes the electrical connection of pilot motor field winding 95 from center tap |8| to either tap I02 or IE3 of transformer 98 secondary winding, by operating either relay 9B or 91'. Hence, the voltage which is applied to the pilot motor field winding 95 will be increased or decreased from the normal operating value by the operation of damping switch 23, and the resulting increase or decrease in pilot motor 93 torque will quickly and smoothly drive the controlled element 5'| into positional agreement with the controlling element Ill, not shown in Fig. 5 but similar to element If] in Fig. 1. With a constant voltage applied to the armature 94, the torque produced by the pilot motor 93 is proportional to the voltage applied to the field winding 95.

In the arrangement of Figure 6 wherein the control system of this invention is shown adapted for use with a direct current pilot motor I04, the pilot motor armature M5 is electrically connected to the direct current supply, and the field wind ing N35 is energized from the voltage divider I01, which has its center tap H) electrically connected to one end of field winding M5. The free running speed of the pilot motor N14 is higher than any speed required for the operation of the system, so any increase in the voltage which is applied to the field winding will increase the torque of the pilot motor, and thereby increase its acceleration.

Follow-up heads l8 and i9 control the selection of either end tap |08 or H19 of voltage divider Hi1, and damping switch 20 directly changes the normal operation voltages, which are applied to the pilot motor field winding M5, by short circuitin voltage divider taps H0, or taps I I0, I l2. Hence the voltages applied to the pilot motor field winding will be increased or decreased from the normal operating value by the operation of damping switch 20, and the resulting increase or decrease in pilot motor torque will drive the controlled element quickly and smoothly into positional agreement with the controlling element, not shown. With a constant voltage applied to the armature I05, the torque produced by the pilot motor I04 is proportional to the voltage applied to the field winding I06.

It is to be noted that the system adaptation illustrated in Figure 6 differs from the systems illustrated in Figures 1 and 5, in that relays under the control of the damping switch are not required, and the damping switch contacts 64 and 65, instead of being electrically connected to the respective long contact segments of the follow-up heads, are electrically connected directly to the respective taps H2 and [H of the voltage divider I01.

It will be seen that the damped control system of this invention is very simple in construction, but very effective and efiicient in operation, and can be used for reproducing with shaft 51 the movements of any controlling element such as a handwheel, lever, telescope, and the like, or for adjusting a remote controlled pilot device, such as motors 2!, 93 or I04, in accordance with impulses developed by photoelectric devices, thermostats, valves, floats, air or fluid flow meters and apparatus, and the like, as will be readily understood.

Although certain specific embodiments of the invention have been illustrated and described herein, the invention is not intended to be in any way limited thereby, but is capable of numerous changes in form and detail Within the scope of the appended claims.

We claim:

1. A system comprising a controlling element, a controlled element governed thereby, a motor connected to said controlled element, a source of voltage for the said motor, fine control means responsive to small angular deviation between the controlled element and the controlling element for closing a circuit from said source to the motor, coarse control means responsive to relatively large deviation between the said controlled element and controlling element for closing a circuit from said source to the motor and for disconnecting the fine control means from said source, mechanism for changing the Voltage supplied to said motor from said source, and means actuated by one of said means in response to relative angular movement between the said controlled and controlling elements for actuating said mechanism to change the voltage supplied to the motor to accelerate it rapidly in a direction to reduce the said deviation.

2. A system comprising a controlling element, a controlled element governed thereby, a reversible motor, a voltage supply, an input transformer for the said motor having a plurality of taps, a pair of relays each having contacts to connect the motor to certain of said taps, fine control means responsive to a predetermined small degree of positional disagreement between the controlling and controlled elements for connecting the motor to said supply to drive the motor in the direction of the controlling element, coarse control means responsive to a positional disagreement in excess of said predetermined degree between the said elements for rendering the fine control means inoperative and for connecting the motor to said supply to rotate it in the direction of the controlling element, a damping switch responsive to a differential velocity between said elements, said switch comprising a pair of spaced contacts driven by the controlled element and a movable contactor adapted to selectively engage the said contacts and connections between each contact and one of said relays, whereby said relays change the voltage applied to the said motor to accelerate it in the direction to reduce the said positional disagreement.

ARTHUR P. DAVIS. GEORGE AGINS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,971,703 Carney Aug. 28, 1934 2,103,287 Howard Dec. 28, 1937 1,508,796 Kaminski Sept. 16, 1924 1,559,525 Murphy Oct. 27, 1925 1,651,852 Trevor Dec. 6, 1927 FOREIGN PATENTS Number Country Date 702,932 France Feb. 2, 1931 

